I recently inherited an Apple II+ (RFI rev), and it seems to boot fine, but it has some serious vertical lines on the video output. I've been troubleshooting to the best of my ability, and have had no luck whatsoever getting it to work.
Things I've done so far:
- Replaced UA3, UA9, UB2, UB10
- Verified correct frequency and voltages on 14MHz, 7MHz and LD194 clocks
- Verified power and ground connections to the above chips
- Verified continuity between relevant UA3 pins and the character ROM
- Tried all 3 rows of RAM in the boot row to verify no chips are bad
- Resocketed processor and all 6 D/E/F ROMs
- Tried adjusting video and color trim pots
I'm at my wit's end with this, if anyone has any idea what could be causing it I'd really appreciate the input. I've attached pictures of the board and video output to this post; the video starts out like the first picture with the bars made of dots, but they transition to being solid within a second or two of being booted up, faster if it has been on for a while and only just restarted. Certain keypresses do work so I do believe it's booting up ok, just seems to be an error somewhere in the video circuit.